Wind turbine tower foundation containing power and control equipment

ABSTRACT

A tower foundation is provided having at least one cavity formed within the foundation. At least a portion of the cavity is located below ground level, and the cavity contains electrical equipment.

BACKGROUND OF THE INVENTION

This invention relates generally to tower foundations. In particular butnot limited thereto, the present invention relates to a tower foundationfor a wind turbine where the foundation includes the power and controlequipment.

Recently, wind turbines have received increased attention asenvironmentally safe and relatively inexpensive alternative energysources. With this growing interest, considerable efforts have been madeto develop wind turbines that are reliable and efficient.

Generally, a wind turbine includes a rotor having multiple blades. Therotor is mounted to a housing or nacelle, which is positioned on top ofa truss or tubular tower. Utility grade wind turbines (i.e., windturbines designed to provide electrical power to a utility grid) canhave large rotors (e.g., 30 or more meters in diameter). Blades on theserotors transform wind energy into a rotational torque or force thatdrives one or more generators that may be rotationally coupled to therotor through a gearbox. The gearbox steps up the inherently lowrotational speed of the turbine rotor for the generator to efficientlyconvert mechanical energy to electrical energy, which is fed into autility grid.

Several technical installations require a tower or a mast to which theinstallation is mounted. Non-limiting examples of such installations arewind turbines, antenna towers used in broadcasting or mobiletelecommunication, pylons used in bridge work, or power poles.Typically, the tower is made of steel and must be connected to afoundation made of reinforced concrete. In these cases, the typicaltechnical solution is to provide a large, solid reinforced concretefoundation at the bottom of the tower. In typical applications the towerfoundation extends about 12 meters below the ground level, and can beabout 18 meters or more in diameter.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the present invention, a tower foundation isprovided having at least one cavity formed within the foundation. Atleast a portion of the cavity is located below ground level, and thecavity contains electrical equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wind turbine to which the embodiments of the presentinvention can be applied.

FIG. 2 is a cross-sectional view of a tower foundation according to oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the various embodiments of theinvention, one or more examples of which are illustrated in the figures.Each example is provided by way of explanation of the invention, and isnot meant as a limitation of the invention. For example, featuresillustrated or described as part of one embodiment can be used on or inconjunction with other embodiments to yield yet a further embodiment. Itis intended that the present invention includes such modifications andvariations.

FIG. 1 shows a wind turbine to which the embodiments of the presentinvention can be advantageously applied. However, it should beunderstood that the present invention is not limited or restricted towind turbines but can also be applied to tower structures used in othertechnical fields. In particular, the various embodiments of the presentinvention may also be applied to antenna towers used in broadcasting ormobile telecommunication or to pylons used in bridge work. Therefore,although the aspects of the invention will be exemplified with referenceto a wind turbine, the scope of the present invention shall not belimited thereto.

The wind turbine 100 shown in FIG. 1 comprises a tower 110 bearing anacelle 120 on its top end. A rotor including a rotor hub 130 and rotorblades 140 is attached to one side of the nacelle 120. The tower 110 ismounted on a foundation 150. Typically, the tower foundation 150 is madeof reinforced concrete.

The conventional foundation 150 is typically a solid mass of reinforcedconcrete. The power and control equipment (e.g., power transformer,inverter, switch cabinets, etc.) are often housed outside the tower in aseparate enclosure or inside the tower at ground level. When highvoltage equipment is stored inside the tower at ground level a greatdeal of caution must be exercised by the maintenance personnel. Thetower is large inside at the base, but quickly becomes crowded with thehigh voltage power and control equipment. There is not a great deal ofroom for the maintenance personnel at the base of the tower when thepower and control equipment is housed therein. Some of this equipment(e.g., the power transformer) can be hazardous if contacted improperly.Accordingly, it would be advantageous to decrease the risk of harm tomaintenance personnel while keeping the power and control equipmentwithin turbine 100.

FIG. 2 is a cross-sectional view of a tower foundation, according to oneembodiment of the present invention, where the power and controlequipment can be housed within the tower foundation. The tower 110 sitson top of foundation 250. The foundation 250 is located so that amajority of the foundation is below ground level 210. A cavity 220 isformed within the foundation 250 so that a portion of foundation 250 ishollow. Cavity 220 is formed substantially below ground level 210 andsized to accommodate maintenance personnel and power and/or controlequipment (e.g., power transformer, inverter, low voltage distributionsystem, medium voltage distribution system, high voltage distributionsystem, switch cabinets, etc.). It is to be understood that cavity 220could be formed of one or more “rooms”, or be partitioned into multiplesections.

In most known wind turbines, an entry door is accessible via a ladder orstairs near ground level. According to aspects of the present invention,maintenance personnel can access the tower via the conventionalarrangement, but also enter the tower without danger of coming intocontact with hazardous equipment or the power and control equipment. Thefloor level of the entry point is illustrated at 230. An access port orhatch 235 can be provided in floor 230. Alternatively access to basementor cavity 220 could be provided via a staircase and/or doorway (notshown).

The power transformer 240, voltage distribution system 242 and controlpanel 244 can be housed within cavity 220. Additional equipment may alsobe housed in cavity 220 or some of the equipment may be moved into thebase of tower 110 (e.g., control panel 244). One advantage of thepresent invention is that hazardous equipment can be located in a saferposition.

The basement or cavity 220 can be cooled or heated by a variety ofmeans. In one embodiment, ductwork 270 can be routed from the cavity 220up to the interior or exterior of tower 110. Suitable filters can beprovided at the entry of ductwork 270 to prevent particulate matter orwater from entering the cavity 220. Air can be drawn in through ductwork270 by one or more fans 272. The fan 272 can be configured to exhaustair from cavity 220 into the base of tower 110 or to the exterior of thetower.

The tower basement or cavity 220 may also be heated or cooled by othermeans as well, such as a geothermal system arranged near wind turbine100. In the geothermal example, a heat exchanger (not shown) could beplaced in cavity 220 and suitable piping could be connected to the powerand control equipment. Piping could be routed from the heat exchangerdown into the surrounding soil to complete the geothermal system. Inadditional embodiments, the geothermal heating and/or cooling systemcould be of the open loop or closed loop type. The temperature of thecavity will also be more consistent, due to its subterranean nature, andthis reduces the magnitude of the thermal cycles in the surroundingenvironment. The electrical equipment will last longer in thisenvironment of more consistent temperatures and reduced thermal cycles.The environment in cavity 220, as compared to the interior of tower 110,will be cooler in the warmer seasons (e.g. summer) and warmer in colderseasons (e.g., winter). As can be seen, there are many benefits tostoring electrical equipment in the basement or cavity 220 of foundation250.

In additional aspects of the present invention, separate zones can becreated for housing different types of equipment. A first zone could becreated above floor 230 for non-hazardous equipment (e.g., the controlpanel). A second zone could be created in cavity 220 for medium riskequipment (e.g., low voltage distribution system), and a third zonecould be created in cavity 220 for more hazardous equipment (e.g., powertransformer). The first zone is separated from the second and thirdzones via floor 230. The second and third zones may be separated fromeach other via a partition or wall within cavity 220, or be spaced apartfrom each other and visual indicia may be used to indicate theseparation.

An additional benefit the present invention provides is that thesensitive electrical equipment can be isolated from the tower vibrationsby being housed and mounted within cavity 220. Tower vibrations cancause accelerated aging of electrical components or equipment. Thebasement or cavity 220 can be used to insulate the sensitive equipmentfrom undesired vibrations. To provide even further vibration isolation,the equipment can be placed on vibration absorbing mounts in cavity 220.

The storage of power and control equipment in the cavity 220 offoundation 250 also provides a more secure storage location. The mainentry door of tower 110 provides a first barrier and the access door 235provides a second barrier to the equipment in cavity 220.

If desired, dehumidifying equipment can be included within the cavity220 or in the ventilation system of 270 and 272. In very humidenvironments (e.g., coastal or tropical regions) this may be a desiredaddition.

Additional equipment could also be stored within cavity 220. Forexample, power storage devices could be located within cavity 220 forstorage of excess or off-peak power generation. The power storagedevices could be comprised of batteries (e.g. sodium-sulfur batteries),massive electricity storage (MES) devices, compressed air storage,capacitors, and other suitable devices or systems. Grid connectequipment could also be housed within foundation 250.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A tower foundation, comprising: at least one cavity formed withinsaid foundation, at least a portion of said at least one cavity locatedbelow ground level; and electrical equipment contained within said atleast one cavity.
 2. The tower foundation of claim 1, wherein said towerfoundation supports the tower of a wind turbine.
 3. The tower foundationof claim 2, wherein said electrical equipment comprises one or more of:a power transformer, voltage distribution equipment, inverter, andcontrol panel.
 4. The tower foundation of claim 1, further comprising anaccess door located near an upper portion of said at least one cavity,wherein said access door permits access to an interior of said at leastone cavity.
 5. The tower foundation of claim 1, further comprising: aventilation system, said ventilation system provided to heat and/or coolsaid at least one cavity.
 6. The tower foundation of claim 5, whereinsaid ventilation system comprises one or more fans.
 7. The towerfoundation of claim 5, wherein said ventilation system comprises ageothermal heating and/or cooling system.
 8. The tower foundation ofclaim 1, wherein said at least one cavity comprises one or morepartitions, said one or more partitions used to separate said electricalequipment.
 9. The tower foundation of claim 1, further comprising: oneor more vibration isolating mounts; wherein, said electrical equipmentcontained within said at least one cavity is supported by said one ormore vibration isolating mounts.
 10. The tower foundation of claim 2,further comprising: at least one energy storage device located withinsaid at least one cavity; wherein said at least one energy storagedevice can be used to store power generated by said wind turbine. 11.The tower foundation of claim 10, wherein said at least one energystorage device is comprised of at least one or more of the followinggroup: a battery, massive energy storage device, a capacitor, andcompressed air storage.